Parallel EEPROM Programmer
This board was made to program or read AT28C256 or AT28C64B parallel EEPROM. For digital electronics these chips can be very useful, they can be used to mimic the functionality of other chips if you don't have them at hand or simplify designs that require lots of glue logic between parts of your design. They are addressed via parallel instead of a serial protocol like i2c or spi. This means you can use them to simplify designs that would require many 4000 or 7400 series chips. The parallel EEPROM can be used where it would be unreasonable to use a large amount of 4000 or 7400 chips but before you might start considering a CPLD or FPGA for your design.
The schematic is fairly simple there is a 7805 voltage regulator to keep the supply at 5v. some dip switches to set the address a jumper that will set output enable to low for reading the address and high for writing. Some headers for test purposes. Some leds to show you the output of the address you are reading or writing and a push button to program the EEPROM.
Board layout shown has the leds on the left below the test points, the address switches and their pulldown resistors are above the test points. on the right there is the switches to set the output of the address when you are programming the EEPROM below the regulator is the switch and timing circuit for writing to the selected address.
